Professional multi-media systems and multi-media control can be applied in environments as diverse as concert halls, stadiums, clubs, convention centers, conferencing centers, open air spaces, houses of worship, meeting spaces (government-, corporate-, and private-sector), recording studios, film, television, radio, ENG (electronic news gathering), and two-way communications, for example. Professional multi-media systems focus on the capture, monitoring, storage, and/or reinforcement of one or more audio or visual signals generated by one or more sources, which can be animate or inanimate. This process can occur in real-time requiring low latencies (below human recognition). Audio signals are captured via microphones, for example, which convert the sound waves comprising the audio signal into electrical impulses. These impulses are typically transmitted to a multi-channel control surface via cables. Each microphone is assigned a unique channel within the control surface. Visual signals are captured by video cameras, digital cameras, analog cameras, projection systems (e.g., LCD projectors), scanners and the like, and are similarly transmitted. The control surface allows an audio/visual engineer to modify the incoming multi-media signals and blend these incoming channels into fewer output channels should this be desired. This output can be sent to a storage device (in the case of recording), speakers (in the case of venue with a sound reinforcement system), visual interface or a combination thereof, for example. The engineer can also use the control surface to create a monitor mix from the incoming audio signals independent of the primary mix. This monitor mix is customized to meet each performer's personal preference, then transmitted back to each respective performer so each can manage his or her own performance.
Historically, routing of multi-media signals has been accomplished through a wired environment using cables and patch panels to connect the various pieces of equipment (microphones, cameras, control surfaces, processing equipment, storage devices, displays and speakers, for example). This requires significant resources to install and manage, including large amounts of supporting equipment and facility infrastructure capable of routing cables and housing and cooling all of this equipment, as well as significant power requirements and conditioning. Over the past several years, the traditional wired environment has been challenged by wireless technology, allowing more flexibility in arranging and locating equipment and reducing wire management cost over the traditional wired environment.
Two examples of wireless audio solutions are wireless microphone systems and wireless IEM (in ear monitoring) systems. The typical wireless microphone system consists of a transmitter (which can be handheld or a body pack, for example) and a receiver with a one-to-one correspondence, i.e., one transmitter to one receiver. The typical wireless IEM system consists of a receiver (e.g., body pack) and one transmitter. This system, like the wireless microphone system, has a one-to-one correspondence between the transmitter and the receiver.
Wireless Microphone Systems
Today's wireless microphone systems are limited to unidirectional transmission, broadcast over the very-high frequency (VHF) or ultra-high frequency (UHF) band, using FDM (Frequency Division Multiplexing). With the exception of a few products, today's systems are analog, not encrypted, and have a wired analog interface with control surfaces such as consoles. Their range is typically 300 feet and, in some cases, extends upwards of 1,500 feet (line-of-sight).
Management of the transmitter's parameters is discrete. Controls for managing body pack and handheld transmitter parameters are located on the unit. The receiver can monitor some or all of the transmitter's parameters but can not change them. The receiver typically has a small display (LCD and/or LED) that displays receiver parameters and some or all of the transmitter's parameters. Since the receiver only monitors transmitter parameters, the engineer informed of the parameters must then physically interact with the transmitter to adjust the transmitter settings or inform an assistant or stagehand to adjust the transmitter.
A recent trend in wireless microphone management is the introduction of Ethernet LAN (Local Area Network) technology to link one or more receivers (e.g., base stations), via a router or switch, to a laptop computer that provides a GUI (graphical user interface) for monitoring and adjusting receiver parameters and monitoring transmitter parameters. This allows remote monitoring of the transmitters and remote monitoring and adjustment of the interconnected receivers. The LAN does not provide bi-directional communication between the transmitter and its receiver. Because bi-directional communication is lacking between the transmitter and the receiver, controls related to the body pack and handheld transmitters reside within each unit. Such distributed control and unidirectional communication hinders the ability to effectively manage the system remotely. Hence the system still requires the engineer, assistant or stagehand to physically interact with the transmitter in order to modify the transmitter's parameters.
External ¼ wavelength antennas are typically used for body pack transmitters while internal or external antennas are found on handheld transmitters. Receivers have a broader selection of antennas ranging from passive omni-directional to powered directional antennas. In most products, these antennas support some form of diversity architecture ranging from the use of two antennas feeding a signal radio to two antennas feeding two independent radios. Additionally, transmitter power consumption has continued to trend downward, extending the operating life of these devices. Transmitter operating time currently ranges from 8–14 hours using primary batteries (typically alkaline). Operating time is somewhat less with secondary (rechargeable batteries).
While wireless microphone systems having the above basic capabilities are known and currently available, analog to digital signal conversion for wireless microphone systems has only recently become available in a very limited number of products. For example, Lectrosonics, Inc. of Rio Rancho, N. Mex. offers a digital system designed for ENG and the film industry. This product offers 128-bit encryption. The transmitter converts the analog microphone signal to a digital signal. The analog signal is sampled 44.1 k times per second with a resolution of 24-bits. It is compressed to 20-bits and encrypted before being transmitted to the receiver. The receiver performs digital to analog signal and AES (Audio Engineering Society) conversion. The digitized signal is broadcast over an FM carrier in the UHF band.
Zaxcom, Inc. of Pompton Plains, N.J. offers a digital wireless microphone system aimed at ENG and the film industry that uses the transmitter to convert the analog microphone signal to a digital signal before transmitting it to the receiver where it is converted back to an analog signal. This product uses a proprietary modulation over the UHF band. The analog signal is sampled at 96 k bits per second with a resolution of 24 bits. Operating time per charge is 4–6 hours.
A wireless microphone system from Beyerdynamic GmbH of Heilbronn, Germany is designed for meetings and conferences and provides bi-directional transmission. It operates in the 2.4 GHz band and uses DSSS (Direct Sequence Spread Spectrum) modulation and is, most likely, based on the 802.11b wireless LAN standard. The control box (i.e., base station) can support up to eight (8) wireless cards and multiple wireless microphones. System bulkiness and specifications limit its use to conference environments—e.g., it requires a proprietary microphone, twelve (12) AA batteries per transceiver, and has a frequency response of 70–10 kHz.
Wireless In-Ear-Monitoring (IEM) Systems
Today's wireless IEM systems are limited to unidirectional transmission. They broadcast an analog signal over the very-high frequency (VHF) or ultra-high frequency (UHF) band using FDM (Frequency Division Multiplexing). They are typically not encrypted. Their range is typically 300 feet (line-of-sight). The typical system consists of a receiver (body pack), transmitter, and an ear apparatus, such as ear pieces or earbuds. Receiver and transmitter have a one-to-one correspondence—i.e., one receiver to one transmitter. Typical frequency response is 40–15 kHz.
Management of the various functions is discrete with controls for managing the wireless receiver (body pack) functions located on the receiver. The transmitter monitors overall system functions and is unable to initiate a change in the receiver's parameters. Receiver battery life is typically 4 to 6 hours with some exceptions exceeding 14 hours. Unlike wireless microphone systems, current IEM systems do not incorporate Ethernet technology into the transmitter resulting in the inability to remotely monitor the IEM system. IEM systems use a wired analog audio interface with control surfaces such as consoles. Further, current IEM systems do not integrate a wireless microphone system of any type, provide analog to digital or digital to analog conversion, signal encryption, bi-directional transmission, remote monitoring, or remote management.
In one aspect, the present invention provides bi-directional, full duplex communication through digital wireless technology, thus enabling remote system management, and conversion of transmitters into transceivers (i.e., clients) and receivers into base stations (i.e., access points). The present invention employs digital technology to provide an encrypted audio and/or visual signal, user selected audio quality ranging from CD to DVD-A/SACD quality and user selected video quality such as HDTV or SDTV, for example. The present invention also permits user selectable formats (PCM (pulse-code modulation) or DSD (direct stream digital)). The present invention further provides a remote management solution to monitor and adjust transceivers, base station and other system components remotely from a computer with the system's management software or a control surface. The present invention integrates the wireless audio, visual and IEM systems into a single communication system, and extends system range up to 1,000 meters (line-of-sight). The present invention also creates a one-to-many correspondence between base station and transceivers (receiver and transmitter, respectively based on current industry technology) i.e., one base station to many transceivers. This is beyond the current systems, which are unidirectional, analog, stand-alone, limited in range, one transmitter to one receiver, and have limited audio and visual quality.